83 Heritage Special petcock leaks like a sieve

[turkeysandwich]

Hey, so I am trying to get my bike going for the season but the petcock is just letting the whole tank drain right into the carb at a crazy rate. From what I understand this is a vacume petcock on my bike and I was curious if I switch to a gravity petcock will there be issues?

 

[nj1639]

On, off, reserve.
Just make sure you cap off the nipple on the manifold that provides the vacuum for your current petcock.

Edited for spelling and redundancy......

 

[CoconutPete]

No issues, I have a regular petcock instead of 2 vacuum petcocks on mine.

 

[fredintoon]

Hey, so I am trying to get my bike going for the season but the petcock is just letting the whole tank drain right into the carb at a crazy rate. From what I understand this is a vacume petcock on my bike and I was curious if I switch to a gravity petcock will there be issues?

Hi Turk and welcome,
Yes, stock XS650 vacuum petcocks don't have a manual "OFF" position
and the list has mebbe a 70% "switch them to manual" consensus.
And for us cheapskates, there is a cheap fix.
File off the little nubbin that stops the petcock handle from going all the way round.
File the petcock handle a tad shorter so it'll point straight up without hitting the gas tank.
UP is a true OFF position for XS650 vacuum petcocks.
And perhaps you have another problem too.
Even with a leaky vacuum petcock or a manual petcock left to ON your whole tank should NOT
"drain right into the carb(s?) at a crazy rate" unless the carb float bowl level control needle is shot.

 

[ThatXS650Guy]

Have you taken the stock petcock apart to see why it's leaking? Might just need some TLC. There is a great petcock rebuild tutorial in the tech section.

 

[5twins]

Yes, there is a spring-loaded plunger with an o-ring on it connected to a small rubber diaphragm on the back of the petcock. The vacuum signal sucks this open and fuel is allowed to flow. Maybe that plunger o-ring is just shot, or maybe it's seat in the body is all dirty. I would be taking it all apart. It don't work anyway so what have you got to lose?

 

[yamageddon]

The vacuum petcock was the first that 'left the building' with a dashing swing after I got tired of fidling with it. Yes fuel, no fuel... Can't go wrong with a regular petcock. OTOH: I agree what Fred said: Check the carb first. In case you forget to turn off a regular petcock the tank will drain anyway through your carb. So changing or reparing petcocks is of course not the cure for your problem.

 

[YamadudeXS650C]

Installing early style petcocks on your bike:

http://www.xs650.com/threads/installing-mikesxs-non-vacuum-petcocks-on-later-models.50124/

 

[gggGary]

The 4 hole rubber "valve" is still available from Yamaha about $10 plus shipping online.
If you rebuild use only the genuine yamaha valve. I've never had an aftermarket one work. Yes the rebuild thread is useful.
I have an 81 petcock apart waiting for the valve to come in. I had 79 petcocks that were rebuilt and working but sat 4 years with no gas, went through cleaned and lubed them and they are back on duty.

 

[650Skull]

Ha, Ha, ha, Dueling threads